This invention relates to a low friction, heavy-duty lockset, and especially relates to a lever type lockset which employs a roller housing within the main housing thereof.
Previously, many lever type locksets have employed a slidable type housing (20) (for pulling a lockset) within a main housing (10), as shown in FIGS. 7 and 8. This type of structure has the drawback that there is a certain amount of unavoidable friction between the slidable housing (20) and the main housing (10). Ordinarily, this friction is of no major consequence. However, to a handicapped user this relatively small amount of friction (or resistance) might be enough to prevent the user from turning the handle.
A second problem with conventional lever type locksets can also be seen in FIGS. 7 and 8. Most spindles (30) have had small, rectangular cross-section protrusions (301) set thereon for forcing a slide plate (201) backwards and thereby pulling back a latch (not shown) so as to allow the door to be opened. However, since the force is applied at the distal radial end of the protrusion (301), there is a corresponding bending moment and shear force where the protrusion (302) meets the surface of the spindle (30). The bending moment and shear force, in turn, create a lot of stress at point (302). After many cycles of usage, the protrusion (301) can easily be broken due to fatigue failure.
A third problem with conventional lever type locksets is that the slide housing (20) therein was formed as one piece. However, in order to form as one piece, the thickness of the side plates (201) had to be reduced to facilitate manufacture thereof. This "reduced" thickness has in turn also caused stress and/or bending failures.
It is the purpose of this present invention, therefore, to mitigate and/or obviate the abovementioned drawbacks in the manner set forth in the detailed description of the preferred embodiment.